330 



Belling. 



mum is 27 (or 10, if we omit LV-92) per cent of ovules aborted for 

 the normal plants. This does not hold, however, for the semi-sterile 

 plants. The percentage of full pods in the fertile plants varies be- 

 tween 12 and 65: for the semi-sterile plants it is below 3, as required 

 by theorv. 



Velvet by Yokohama. — Six fresh pods were examined from all 

 plants which bore pods between August 28 and September 17, 1913. 

 The plants of this generation segregated into those \\1th whitish pubes- 

 cence on their shoots, and those with black tomentum on the shoots 

 and young leaves, in the usual ratio of 13 : 3. The latter plants usually 

 had imperfect pollination (as has been stated to be the case in the Lyon- 

 Velvet cross), and are to be considered separately. 



The pollen of this generation having been thoroughly examined, 

 the question arose whether the semi-sterility of the embryo-sacs was 

 alwaj-s linked with semi-sterility of pollen-grains, or whether the two 

 occasionally segregated apart. 



It has been shown that the distal half of the pod affords a more 

 accurate indication of its state as to fertility or semi-sterility than the 

 whole of the pod, because of the frequent non-development of the basal 

 ovules in the fertile plants. Hence only the first three seed-places in 

 each pod are considered here. 



Out of the plants with wliite pubescence whose pods were examined, 

 the 99 plants which had good pollen had, out of the 18 ovules in the 

 distal halves of 6 pods, a number aborted varying from to 6, with 

 an average of 9 per cent. The 70 plants which had semi-sterile pollen 

 had, out of a possible 18, a number of o^^lles aborted var\ing from 3 

 to 12, with an average of 42 per cent. 



Number of ovules aborted in the first three seed-places of six pods. 

 (Plants with wliite pubescence only.) 



Thus the number of undevelojjed ovules is increased in the normal 

 plants from a theoretical o to an average of 9 per cent for the apical 

 half of the pod, probably by local lack of nutrition: while in the jdants 



